Remember back in 2005 when Israel requested 100 GBU-28 “bunker-buster” bombs? No, neither do most people. It was in Reuters, as documented here and here, but did not get much attention or spin.

April 27, 2005 09:28am
Article from: Reuters

THE Pentagon has notified Congress of a proposed sale to Israel of 100 guided bunker-busting bombs, a move that analysts said could prompt concerns about a unilateral Israel strike against Iran.

A vague and weakly cited article in the Telegraph was posted a year earlier. It claimed 500 BLU-109 (dumb bombs) might be acquired by Israel to use in Syria or Iran, but it was all speculation.

A report in 2006 mentioned bunker-bomb evidence in Khiam, Lebanon:

The special report was triggered by the radioactivity measurements reported on a crater probably created by an Israeli Bunker Buster bomb in the village of Khiam, in southern Lebanon

This also did not get much attention, it would seem. Today Israel is getting more press for its request for 1,000 GBU-39, a small and lightweight bomb. The AP has the story, posted on Yahoo! news and Salon just an hour ago:

Shlomo Brom, the Israeli military’s former chief of strategic planning, noted an increasing tendency to place weapons underground.

In Israel’s 2006 war against Lebanon’s Hezbollah guerrilla group, “one of our problems had been that they put many of the rocket launchers in bunkers and fortifications underground ,” Brom said.

[…]

Past U.S. sales of bunker-buster bombs to Israel have been construed as a veiled threat against Iran’s nuclear program.

But Brom and Shapir said they did not think they would be used against Iran, where key nuclear facilities such as the uranium enrichment plant at Nantanz are buried deep and hardened by yards of concrete.

“You would need something a lot heavier,” he said. The GBU-39 can penetrate 6 feet of concrete, and “6 feet is not enough,” he said.

The GBU-39, known as a small diameter bomb, perhaps best directed at tunnels and caves used for hideouts or munitions.

Weapon weight: 285 pounds (130 kg).

Warhead: 206 lb (93 kg) penetrating, blast fragmentation.
* 50 lbs (23kg) of high explosive.

Warhead penetration:

* “six feet of reinforced concrete”.
* “more than three feet (1 m) of steel-reinforced concrete”.

Compare that with the much larger GBU-28, which was the subject of the 2005 story by Reuters that I started this post with:

The weapon weighs 4,700 lb (2,130 kg) and is over 19 ft (5.8 m) in length (TI).

Brom’s assessment makes sense based on this data. The bombs are getting smaller and smarter, which suggests to me they will be useful for strategic positions, rather than wiping out giant installations or nuclear bunkers. The only exception I could think of is that smaller means more, so a series of penetration bombs fired on the exact same spot could penetrate far more than a single giant bomb.

However, a complicated combination shot with multiple small bombs makes less sense in terms of risk than a single big shot, based on my pool-playing experiences. Thus I think the latest request for GBU-39 should not be automatically assumed to be relevant to Iran’s nuclear program. The “bunker buster” label is just probably too broadly used.